Body Fat Calculator: API and MCP

Body Fat Calculator over REST and MCP: input fields, limits, outputs, one example request and its real answer. Free, no sign-up.

Id: health.body-fat
Version: 1.0.0
Access: Free
Tool page: Body Fat Calculator
Schema: GET /api/v1/tools/health.body-fat

Input

Field	Type	Constraints	Description
`sex` (required)	string	female \| male	Sex
`weight` (required)	number	≥ 20, ≤ 350	Weight (kg)
`height` (required)	number	≥ 120, ≤ 230	Height (cm)
`neck` (required)	number	≥ 20, ≤ 80	Neck circumference (cm) · Just below the larynx, with the tape level.
`waist` (required)	number	≥ 40, ≤ 250	Waist circumference (cm) · Men: at the navel. Women: at the narrowest point. Do not pull your stomach in.
`hip`	number	≥ 50, ≤ 250	Hip circumference (cm) · Required for women only. Measure at the widest point.

Output

Field	Type	Description
`bodyFat`	number	Body fat (%)
`fatMass`	number	Fat mass (kg)
`leanMass`	number	Lean body mass (kg)
`essential`	boolean	Essential fat level: below 6% for men, 14% for women (ACE).
`athletes`	boolean	Athletes: 6–13% for men, 14–20% for women (ACE).
`fitness`	boolean	Fitness: 14–17% for men, 21–24% for women (ACE).
`average`	boolean	Average: 18–24% for men, 25–31% for women (ACE).
`obese`	boolean	Obese: 25% or more for men, 32% or more for women (ACE).

Example request

{
  "input": {
    "sex": "male",
    "weight": 80,
    "height": 178,
    "neck": 38,
    "waist": 90
  },
  "locale": "en"
}

Example answer

{
  "output": {
    "bodyFat": 20.1,
    "fatMass": 16.1,
    "leanMass": 63.9,
    "essential": false,
    "athletes": false,
    "fitness": false,
    "average": true,
    "obese": false
  },
  "steps": [
    {
      "id": "girth",
      "formula": "girth = waist − neck",
      "substitution": "girth = 90 − 38",
      "value": 52,
      "unit": "cm"
    },
    {
      "id": "density",
      "formula": "body density = 1.0324 − 0.19077 × log10(girth) + 0.15456 × log10(height)",
      "substitution": "body density = 1.0324 − 0.19077 × log10(52) + 0.15456 × log10(178)",
      "value": 1.05286
    },
    {
      "id": "bodyFat",
      "formula": "body fat = 495 / body density − 450",
      "substitution": "body fat = 495 / 1.05286 − 450",
      "value": 20.1,
      "unit": "%"
    },
    {
      "id": "fatMass",
      "formula": "fat mass = weight × body fat",
      "substitution": "fat mass = 80 × 20.1%",
      "value": 16.1,
      "unit": "kg"
    },
    {
      "id": "leanMass",
      "formula": "lean mass = weight − fat mass",
      "substitution": "lean mass = 80 − 16.1",
      "value": 63.9,
      "unit": "kg"
    }
  ],
  "meta": {
    "toolVersion": "1.0.0",
    "locale": "en"
  },
  "citation": {
    "url": "https://hesaplayici.com/en/health/body-fat-calculator",
    "title": "Body Fat Calculator"
  }
}